To improve nitrate ion removal from water, we focused on synthesizing and evaluating a new polymer composite adsorbent based on gum tragacanth (GT) grafted with polyimidazolium (PIL-MGT). For this purpose, 1-butyl-3-vinylimidazolium chloride was synthesized to be grafted on the polymer surface. In the next step, GT was modified using maleic anhydride which led to the formation of the final adsorbent derived from the reaction between the ionic liquid and the modified GT. The FT-IR, FE-SEM, and TGA analyses were used to characterize synthesized compounds. The PIL-MGT adsorbent achieved a maximum removal efficiency of 95.66% and an adsorption capacity of 14.35 mg/g at pH 5, with a 20-min contact time and an initial nitrate concentration of 30 mg/L using 40 mg of adsorbent. To investigate the selectivity coefficient for nitrate ions removal, other ions such as bicarbonate, phosphate, chloride, and sulfate were also added to the nitrate solution. The results showed that nitrate ion removal was decreased the most due to the presence of chloride and the least by phosphate ions. The reusability of PIL-MGT was assessed through an adsorption/desorption experiment, and the results demonstrated consistent loading efficiency after six reuse cycles. Several models of isotherms and kinetics were undertaken, a second-order model best described the adsorption kinetics and the equilibrium data conformed to the Langmuir isotherm model. Finally, with the disk diffusion method, the antimicrobial properties of the adsorbent were investigated.
